Fluid-pressure brake



Aug'zl, 1928.

T. H. THOMAS ET AL IIIll lll 7 .l 5 3 3 Z 2 Y 2 MSWI, 643 44. .ow/Www .7mm E .|||V|. A A, ER l s R .Il lu l w a N. M I 2 .nvrlrll 1.` w @www W 4 w l mAD M mi 7 e NMU 5l 5 H m 9M m3 mTcw 7 L .S a UWE 8 M IRR 6B IE qq 5V 0IA- g l s .w W, l m R A Wl: r .I4 W .NHV w. M H a 4 8 L. \O .4 33 4 3 m n o@ n s 9 9 r m o 8M 7 ,w m mm .L P .mw M m .o 7 l M OO n 6 f 7 a 44e a m m a s a 8 M f LI'II L e Patented Aue. 2l, 1928;v

goigiif'riin srarrs i azvrir-iri ortica THOMAS n. THOMAS. or nnenwoon, AND CLAUDE A. NELSON, OF WILMERDING, PENN- SYLVANA, ASSIGNORS TO 'THE VESi'ENGI-SEAIR' BRAKE COMPANY,

OF' WIL- iunnnrrie, PENNsYLvANrA., A courent-errori OrfrnnivsvtvANIA.

nLUm-rREssUnE BRAKE.

Application iiiedjoctoberes, 1927,V seriali uro. 224,867'.`

Y automatic means for `separating the second reduction reservoir from the first reduction reserifoir upon eifecting;I the initial reduction injequalizingr reservoir pressure. p y

Another object of our invention is to lprovide automatic means for maintaining the time elapsing between the .start kof the first reduction and the start of the second reduction within predetermined limits, whichliin# its 'varyas the trainlength varies. ,i Another object oif'our invention isto provide automatic means for varyingfthe degree of time elapsing betweenthe start of the first reduction and the start of the second` reduci tion substantially in proportion to fthe length of thetrain, and regardless ot the degree of leakage offluid under pressure from the brake pipeto 'the atmosphere. Y V

Another vobject ofxour invention is kto en* `vsure a full. and contiiiuous service reduction in brake pipe pressure, in case of failure of the luid `pressuresupply normally furnished to the split i'educt.ion,device Jfor controlling` Athe operation of such device.

`Other Objects and advantages will` appear in the following more detailed description of our invention. i j v yIn the accompanying' drawing, the single ligure is a diagranimaticview of an automatic traincontrol apparatus embodying our-invention. e i e 1,

As shown in the drawing, the automatic train control apparatus may comprise an automatic brake valve device 1, a magnet valve devieeQ anda split reductionvalve device. f

The automatic brake' valve device 1 is of the usual type employed with automatic train control apparatus and comprises a. casing having' achaii'iber 3, containing a rotary valve 4 adapted to be operated by a handle 5. and' also comprises the `usual` equalizing plston mechanism, which includes anV equalizingpiston @and a brake. pipe `discharge valve ,7

adapted to be operated bysa-id pistonffor.: venting fluid under pressure from the 'brake `They equalizing K pipe 8 to the fatmosphere,` piston 6 terms a chamber 9 at one side, which chamber is connectedto an equalizing ,reser voir 1Q through passage 11and at the opposite side said piston' forms a ehan'iber 12 which is connected tothe bra-kepipe 8 through ya pas-v The brake valve casing also has a chamber `14 containing va cut-oft valve 15,. which valve is adapted'` in one positointoseal Ona seat ring 16.y Thecut-of valvel is conf nected by meansof a stem to apistonf17 conq tained in a chamber 18,'` vwhich piston vis adapted to operate the eutfofffvalve,saidpiston beingopposed in outward,movementby the. pressure of a spring-19.

, n Preferablyassociated with the brake valve device is a brake application valve `comprisinter a pistonQO contained in a chamber 21 and a slide valve 22 contained in a chamber 23 and adapted to be operated 'by' saidpiston. The piston 201s opposed in .outward movement bythe'pressure'oi a spring' 24. i f.

, The magnet valve deviceZ comprises a lcasing, containing a magnet adapted tooperate a valve 25` contained in a chamber 26, Lwhich chamber `is connected `to the atmosphere,

in the casing and into a cliamberQS, in which *i i y1,681,561;A

chamber, said valve stein engages a stem 29,

saidlatter .stem extending througlra wall oi the casing andyiuto a chamber 30, wherein` a sprinfr liactson a thrust washer, engaging The controlportion 32 of the splitfreld'uc# tionvalve device comprisesa pistonAv 3,6;con-V tained in a chamber 37 and a piston 38 con` tained in.4 a chamber 39. Said pistons have diilerenty areas, are connected together-by a stem, and are adapted to operate a slide valve 40 containedjinV a valve chamber 41.` The hold-back portion 33 comprisesa `piston 42 contained in achamber `43` and a slidevalve 44 `contained in' a'valve chamber 45,`said slide CJI opposite side a chamber 50. stem 51,-co'ii-4 tained in chamber 50, is carried by said tha-- phragiii, and mounted between two shoulders on said stem is aslide'ValVe 52,'l`whi`cli e valve is adapted to be operated by de-v on`V of the di a pliragm- 48. `(liitv;ard' dey ection oi ysaid diaphragm opposed bythe pressure oi'xay coil spring 53-contai'ned in the Thedelay valve Jportioi'i 35 ollfthe split reduction vdevicey comprises a diaphragm 54 forming a chamber atene side and achamvbery chamber 56 and engaged by the diaphragm 54 Gat the yopposite-'si'de Contained in the isa piston' 57 having centrally depending stein58 extending througha wall in the casing and:n intoanfatmospheric cavity 59 ormed'in y' vsaidcasiiig. `In the chamber 59' the piston stem 58 engages the tinted stemr offa Valve 60,y suclrvalve beingfcoiitained in a 'chamber 61.*

The pressure of acoil'fspring` 62, also contaiiied iii lcliaiiibert, normally holds thevalve 60,` seated. l A spring 63 isiinterposed between the under side 'ofthe piston 57' 'and a wall of the casing and is adapted to normally maintain said ing. Y f c In operation, iiuid under pressure from a main reservoir 64 is supplied tothe rotaryv valve chamber 3 of the brake valve dev1ceto the slide valve chamber 23 of the application valvedevice an d to ytwo `feed valve devices 65 and-66,y through the pipe rand passage A:67.

Fluidy,trom the application valve chamber 23 flows through a port 68 iii-the application pis! ton 'into the piston chamber; 21and from' thence through passage an"d"-p`ipej69y tozthe ch'anib'e'rQS in the magnet valve device. With af trainr operating` in territory inA which; the

track conditions are favorable, the magnet ofv the magnet valve device Q is energized, so that the valve is seated; The fluid pressure thus is permitted-to equalize on the opposite sides of the application-piston Q0, and the pressure oit spring 2'4'tfhen holds the application 'piston' 20 and slide valve position..v I y Fluidatthe usual'ieduce'd pressure carried inthe brake pipe is siippli'edlbythe feed valve device 65' yto'pipe and passage 70, which passagefle'adsfto the seatoftherotary Lvalve 4. fith the brakevalve ingrele'ase position, as

22 in the inner or release show-'vii in `the drawing, Huid from passage, 70` f flows through port-'71 in the rotary? valve 4and passaeje- 72- to the cut-#oft valve` chamber 14 and. 'som'passa'ge 7 @through `cavity' 73 inthe piston in the position'shown in thedrawl `application slide valve 22-arid passage k74 to l the cutsoli valve piston chamber 18. The fluid pressure thus equalizeson the opposing sides of the cut-oli valve k15 and cut-oli' valvefinston 17, so thatthe pressure of springvvl) is perniittedfto-shift the cut-oli valvepiston 17 in- Wardly ,andv unseat the cut-olil valve 15, theree by permitting feed valve fluid fromthe cutott valve chamber 142 to flow past said valve and vrointhencerto the brake pipe 8 and tol the equalizing pistony chamber 12, through.

passage Fluidat feed valve pressure also flowsv l'roiiipoit 71 inthe rotary valve 4 to the equaliziiig piston chamber 9 and to the equalizing reservoir-'10 througlipassage7 5, cavity 76 lin the application slidevalveQQl and pas` sage11.` rlllie fluid` pressure thus becomes l equal on the opposite-sides oil the equalizi'ng. v

pfistonf 6, ywhich :piston theii'lhold's the lbrake pipe discharge valve 7 seated in theusual" manner. f

` With' the ybralte pipedischarge valve 7 seat! ed,'-tli`e contioli'piston ychamber 37 of the split reduction valve deviceisat atmospheric pres!y sure. on ac couiitHof-the connection" through pipe andpassage 7 7 and an atmospheric exe liaiist 'choke plu'g, so th'atf'the pressure of the 'bral-ie pipe iluid acting on lthe gfcoiitr'ol piston 38 iii chamber 39Qholds saidipiston, the

control pistonBG-and the slide valve in the upward position, as shown in 't-lie drawing.

f lViththe application slidevalve '22 in the release position,'tlie charging valve chamber y in Ythe split reductiondeviceris-connected to-,the atmosphereth-rough passage and pipe 79, cavity m said slideV valve and theat inosphcric exhaust passage 81. '#Since the .dia-

pliragm rchamber 490i the chargin'gvalve A passing-e279 through portion i connected to the a chohed'passage U2, the 'fluid-pressure in said diaphragm chamber is' equal to that: inthe valve chamber 50, iso thaty the pressure of,y

spring is permitted toflioldthc charging portion' in "the ]j o-sit'ioii lslioivniii the drawing, iii "which position, 'the hold-back piston `chamber p43 i andy delay vvalve :chamber 61 areconnected to the atii'iosphere through' passage 83, cavity 112 inthe charging valve slide valve 52, passage84', cavityi85'`in the control 'slide y,valve 40 'and vthrough thc choked atmosphericexhaust passageiv The hold.- back piston cliamborbeing thus vented Ato the atmosphere, the prcssure'ofspring 46 is per? initted to hold the hold-hack pistony 42 and slide valve 44ki`n the downward position, inV which position atinfiingA reservoir 87 is con nected to. the atmosphere through-pipe and f y passafgeSS;throughthe valve chamber '45 fand through the atmospheric passage 475;" The i timing reservoir 87 is also connected to the atmosphere by 'Way 'o f the choked passage 105 and-{past'tlie ball checkvalve 111 to the vented passage l83 Siiic-e the diaph'ragnifchamber `r55 oi'f the max' y ,num delay' valve 'portionai's-Acoiil ynetted througholiohetlpassage 89 and past heerser.

a ball' check valve 90 to passage 79, which .is connected to the atmosphere, and` ainaxiinuni delay reservoir 91 is conneeted through pipe and passage 92lo the diaphragm chamber 55,

f hoth said chamber aiidlreseryoir are normally at atmospheric pressure. minimum delaiT reservoir 93 is also normally at atmospheric pressure by reason ol the connection through pipe and passage to the vented 'charging valve diaphragm Chamber elf).

lVith the diaphragm chamber of thel maximum delay yalueportion 35 yenteiflythe pressure oit spring' @Sheltie the delay valve piston 57 in the positioiishoiyn 'in thefdra'ivtion reservoir is connected to the atmosphere through `pige and passa-ge cavity lOQvin rthe rotary valve fl ofthe brake valve device and the exhaust passage 103., i

If a train enters territory in which the track conditions are unfavorable. the magnet in the magnet valve device 2 becomes' de-V enere'ized and operates to permit the pressure oil the coil spring' 8l to unseat the valil'e .25 and tl'iereby pein'iit the fluid under pressure from the application piston chamber `Qi to be vented to the atinospliere.V vThe pressure o'll the lliiid in the aiiplicationyali'c chai'iilier Zithen shifts the application piston 2li and* slide valve flote the downward or application position, against the pressure et 'the colil spring' 24. l fil/'ith thegapplicatioii slide, Valve in ap"` plicution :position` the Cutpll Ayalre piston chamber 18 is rented to the atmosphere through passage jf-l, port ,lill inthe application slideyalyeQQ and the atmospheric haust passage 8l, so that theYopposing` pressure o'lE the lirake ijiipe fluid on the ,Cnt-oft Valve piston 17 is permitted to shiitt said piston outwarijlly an the pressure oit spring' 19,sueh inoveii'ient` ot saidi'piston causing the cut-oft' valve l5 to be also shit'ted outwardly and-seal on the seat ring' i6 and thus prevent further vflow oft tliiid under pressure to the brake pipe 8. The eqnaliziirf;- rese'rif'oirl() and equalizinf;l piston chamber 9 arc connected to the tirst reduction r 9G through passage .115 cavity 7G inthe appli-n cation slide Valve Q2 and passa and pipe 98;'

so that fluid under pressure from the equalizing reservoir is permitted to iloiy to the irst reduction reservoir and thereby cause adecrease in' the pressure in the equalizingpiston chamber 9. The equalismg pistonmechanismy thenl operates in the Wellkuownmanner to causev a corresponding decrease in the pressure ot the brake pipe fluid.

Uponlnioreinent oil the application slide valve toaiiiplication position, lluid atthe ire 'en'iployed in the operation oi' the split reduction device, as supplied by tlieleed yalvedeyiee to pipe and passage'illlll, flows throue'h cavityv 80 in the application slide j bi valve 22 and passage and pipe 79 to the charginf-j valve chamber 50 of the splitreduction deyiee and also from passage 9to the cliai/"gj-` i ing- Valve diaphragm chamber Ll-9 andthe minimum delay reservoir ltl'iroue'hthe ohokedpassaggfe 82. Since `the rate ol" pressure lfiuild-upin theidi-aphragjm chai'i'ilierelf) is retarded liy the clicked portion of passagek the quicker `build-up ot pressure in the valve chamber Odelleets the diaphr gm #l out-vrardlyl and .thereliiy shifts the slideyalre 521e theflelt, inwhieh position, passage S3 is connected to the yalyej cliamber 50,7and,`

fluid lfrom said valve chamberthenows through passage 83 to the .hold-hackpiston chamher d3, to the maximumrelayzyalve chamber Gland through a chokedpassage 105 and pas 88 to a timing rroir dit Since. the ratei'o'll supply to passage 83 ex@ Coeds die rapacity ol? the choked passup/e105,

a' pref-sure in'iinediately buildV up in the holdfbaclr Vpis promptly sli lit the hold-'back piston@ and slide salire del upwardly to thc first reduction position against thepre-ssurc of sprintf 46.r

lr.v lirstrcduction position of the holdibaclrv rslidevalve 4,4, the passages' 98 and 99 .trein thevl'irst and second reduction. reserroiisiflt and 97. resneetiyely, are' disconnected each' otherv so that the ,depji'eeiolillie lirsi, n

ducti on is thereby7 liinfl the Vhrs-t red uetioii i'eserroii9lz.

ln the lirst reductionposition ot 'the holdback slide valve 4.14,. the passage 8S 'troni the timing"reservoir t7? lapped liv said slide valve, thereby i'ierinittiiip; a piessure to he huilti'ip in 'the timingreservoir Si by 'lou' e 105. :il port 199 loro slide yalie K" through' thechoked pz through the charuiiifl` i registers with choked passage llO a nd tluiil 'from the yalye chamber 5l) 'flows througjlisa il clicked passage also lo the timing'. reserroir 8?. The Atiming' reservoir :is tl. Y th rou gli i two choked pu a fast rateofbuild-up ol" pr sure therein.

port 1,06 through the holihliack slide valve elli-registers u h a passoire lll? leading` to `the-contiol slide vulve chamber lll, so tliatksaid chan'ilier is tliei'eby, yentedto vthe Vatn-iosphere vl y Way ol'Y the lioldfback slide valve, chamber-4:5 and theatn'iospherie pas4 sage il for u purpose hereinatterenplained. Fluid If-iuppliedby the feed i-falyedevice 66 to passage E99 also flows to th-ef inaifriinuin tou chamber el?) YWhichaets to rd or lixeil to tliede Vcreuse/Hin the ilfiessure oill the eipializiiiu` i l Voir tluid iiermitted` by the equalization iiilo cli argued sito; s. )wh ich permits Y delay' valve diaphragm'chamber55 through a choked passage 89 and from thence through pipe 92 Vto the maximum delay reservoir `91., wherein a pressure is built up at a predetermined restricted rate.

Ti/'hen the brake pipe discharge valve 7 is lifted', by operation et the equalizing piston 6, to elect a reduction in brake pipe pressure, a portion oi2 the iiuid discharged yfrom the lhrake pipe 8 into the passage 77 is vented tov the atm Vpheie through the choke plug 78.

.The capa ty of said choke plug less than the venting capacity of the discharge valve 7 so that a Jressure is huilt uo through oas a l i ,4 l

"sage and pipe 77 Y on the control piston 36 in"l ch; nher 37, which pressure 'acts to shift the control pistons 8G and 3S and slide valve .-9

downwardly, after the control valve chamber ll is vented'to the atmosphere bv. themov'e- "nient ot. the hold-back piston l2 and slide valve (lll to their upward positien,"in the inannerhereinbefore explained. n f

In the downwardv position of the control slidevali'e lO, the cavity 85 'in said slide valve connects passage 79, which is new connected to the 'feed valve device GG through cavity S9 in the application slide valve 22, to passage Si leadino' tothe seatof the chare'inw'valve slide C3 D D valve 52 and to a ball cheek valve '108, which elieck'valve is lifted, thereby perii'utting duid frompa'ssage 79 to flow through passage and pipe 94 to the diaphragm chamber e9 'o'j the charging valve device and to the mini muni delay reservoir 93, which quickly charges said *chamber and reserif'oir to a pressure equal 'te the pressure of the fluid in the `valve chamber l 50. The ressure ot the coil s rino 53 then kshifts the charging valve diaphra'giii lSaiid rate permitted only through the clicked passage 105.

lWhen the pressure of the brake pipe fluid is` reduced a degree corresponding substantially. to the degree or the lirst reduction in equaliz-v ing` reservoir pressure, the equalizing piston G in the brake valve device operate-s vin theY usual manner to seat lthe discharge .valve 7.

lil/Then'. the ressure ot'4 the fluid dischareedA troni the brake pipe to the control piston chamber 87 is then reduced toa predeter-k mined degree hy flow through the atiiiosi' pheric exhaust choke plug78 in the brake valve device, the pressure et the brake pipe fluidin the' control pistoijiLchambei-"SQ shifts thecontrol pistons 36 and 38 and theslide valve- 40 to their upper position, in which position the timing reservoir. 87, holdback pisrr reduction, `the hol (1l-back piston ton chamber 43, and maximum. delay valve chamber Gl, are vented to the atmosphere through passage S3, cavity 112 in the charging valvefslide valve52, passage 84, cavityA 85 in the control slide valve 4l() and the choked atii'iospherie exhaust passage'S, said timingr reservoirv being connected to the pas-sage 83 by way oipipe landpa'ssager88, past the ball check valve llV and through the choked passage 1.05. y The lpressure of the 'fluid in the timing reservoir and hold-hack piston chainber thus reduces at the same time, and when f *determined degree, the op-y i spring shirts the holdback pistonjfl2 a slide 4valve i4l downwardly, until the caiityzlOQ in said slide verve connects the lirst and second reduction reservoirs 96 and 97 through the passages 98 and 99 i?espectively.r rhe pressure of thefluid'in the equaiizing reservoir 10 and irstreductionl reduced tokr a p v posing pressure i reservoir 96 theni'educes a. 'further .degi'ceby the dovrei-said fluid into the second reduction resem/oir 9i", which further reduction then causes theequalizing piston mechanism in the brake valve device to aG'ain o Jerate and eliect.

a Vc'fii'esponding second reduction inbrake pipe pressure., n p i n z ln ,er to prevent the control portion 82 of the splitrreduc'tion device `from beingr shifted to the lirstreduction yposition while yeiilecting the second i'eduction,'tlie control valve' chamher'll is chargetil with fluid at' brake iipe .pressure `troni the control piston n ot the Aconnection,

l tl'irough passage l0! and l passa-gey 11A/l.r l Tl-ieftluid pressures then acting on `the opposite `sides fof the control piston 38 and oiithe inner side ottli'e'control piston 36 are thus equal and since', ywhen ci recting a brake pipe reduction, the fluid prcsy sure built up in the controlpiston chainlier 37 is always slightly less than. .the pressure of `they brakepipe fluid, the higher tluiil pres sui-erin valve chainher 4l in addition to,A tl rict'ional resistance to movement ot' the con- `lvtrol pistons and ,slide valve liolds'said pisv tons and slide'valve in their normal position. i `This is desirable, since if the control pistons and slide valve ivereperiuitted to inove to tiret reductionpositioni l "le eii'ec the second .i and slide valve Llil would inlz-e shifted toiirst redue tion position anu `thereby prevent the second reduction 'trom '(.iceuringr In order toliinit'the degree of brake vpipe reduction to thatneeessary for causing a full `service applicationl of the brakes, the( brake valve device is turned to lap position, so as to close the vconnection trom the secondy reduc-y tion reservoir 9 7 to the atmosphere through passage 99, cavity 102 in the brake valve ro-k tary valve l and the atmospheric passage 103.

cavity; 113 yin thev hold-- back slide valve in. second reductionposition` lll() ier,

The degree of reduction is thenlimitedto'th.

equalization of thefluid pressure in the equall izing reservoir v10, the rst reduction reserfvoir 96k and the second reductioirreservoir 97.

The period of time elapsing between. the start of the first reduction andthe start of the second reduction in brake pipe pressure should, for a train of a given length, be within certain predetermined:limits under all `conditions,inuorder toensure the proper theslackbetween the cars in a i gathering of y train. Leakage of fluidunderpressure from the brake pipe to the atmosphere hastens the rate at which a brake pipe reduction is made and delays the opening of the discharge valve -application is initiated, and then when the "control pistons and slidevalves 4t() are shifted to their downward position, said timing reservoir is charged ata slower rate through the clickedl passage 105 only. Sineepthe time elapsingbetweenthe initiation of the rbrake applicationan'd the movement of the controlk portion 32 to first reductionpo'sition ispro portional to Vthe degree `of brake pipe leakage, and ysince thedischarge valve zremains open yfor aperiodof time inverselysyproportionalto the degree of brake pipe leakage, the degree of pressure obtained inthe timing yreservoir when charged, varies in proportion to the brake pipe leakage and the time dur ing which the timing reservoir isy being charged `varies inversely tofthe degree of brake pipe leakagefso thatin the case .of brake pipe leakage7 the timing reservoir becomes` charged to a higher pressure ina shorter period of time than would be the case if the brake pipe were substantially air tight;

Since, inthe caseot brake pipe leakage, the

discharge valve remainsy open for a shorter period of. time, the higher timing reservoir pressure starts toV reduce sooner than would a lower timing reservoir vpressure resulting- -iLrom the .ei'iect ot less brake` kpipe leakage.

In a train of a given lengtlnthis results in the vtiming-reservoir pressure always becoming reduced to thedegree `at which the second reduction is initiated in the same time, or Within certain predetermined time limits,-fromV the start ofthe iirst reduction.

Incasethe brake pipe leakage is so severe 'as to cause an initial reduction in brake pipe yressure as astvas the pressure in the equalizing reservoir 10 `is. reducet they discharge valve 7 and the control portion 32 of the split reduction device will obviously not operate duringth'e `first reduction to 4time the `nieveinent ot the hold-back portion 33 for initiating the second reduction, but under Asuch a conditionthe second reduction in equalizing reservoir pressure is started within the proper time limit onacc'ount of the timed build-up of fluid pressure mathe charging valve diaphragm lchamber 419 and the delay reservoir 98, through the eholzedpassage `82. lVhen the YHuid piessure in' said'cliainber and reservoir becomes substantially equal to the fluid pres-Y sure in the charging :valve chamber 50, Lthe lpressure of spring 53 deiiects the diaphragm i8 and the slidevalve 52 is then shifted by the diaphragm to its inner position, in which position the Vfluid 'under pressure in the holdback piston-,chamber 43' and in the vtiming reservoir 87 is vented to the Aatmosphere through passage 83,.cavity 112 in the chargf "inglvalve slide valve `52, p`assage'84, cavity 85 Vin the control slide valve i0 andthe choked exhaust passage 86. Thus7 when' theiluid pressure in the hold-back.pistonchamber 43 isvreduced to a predetermined degree, the pressure Loi' spring i6-shifts the hold-back piston 42 and slide valve 4A; outwardly to the second i'eduction position,l in whiclrposition the seeondreduction in equalizing reservoir pressure is effected. i Y f some of the triple valvesA on thecars in a longvtrain fail to'readily respond to` a fservicei'eduction in brake pipe pressure, as'

'mightoccur it' the triple'valve pistons become stuck in their cylinders,due to thev accuinulation oil dirt or other foreign matter,

a back flow otiiuid under pressiiretrom'the Vauxiliary reservoirtojthe brake pipe occurs.

`Said back ltlow increases the quantity of ilu'id under pressurewhich'liasto be vvented past f ythe openy ldischarge valve `7, and ify the back `flow is sutlicient, the closingk ol*l the discharge valve may be so delayed asto prevent the secondreductionirom starting Within the proper predetermined i time i limit. Under' 4such condition', 'it theseconcl`fie'diiction is :not started within a certainl time, the Huid lpressure in the delay valve diaphragm chamber 55 and the' delay reservoir 1 91 klbecomes suiiicientrto' deflecttheqdiapliragin 54 land .shift the piston 57fdownwardly against the opposing pressure ofspring- (33.' Such move- `ment of piston 57 `unseatsthe 'valve160, which Vpermits venting oi' vthe hold-back piston chamber 43 and timing reservoir S7 tothe atmospheric exhaust chamber 59. The lioldlbackportion 33tlienoperates in the manner hereinbefore" described 'to start thesecond reduction withintlie proper time limit.

The time required to gather the slack in a train varies` asfthe `tiain length varies, 'and since the second reduction of a! tivo kstage reduction can be started assoon'astheslack is gathered, the time to the startet the second reduction can be obviouslydecreased as the train length decreases.` According` toio'ur invention, the time betweenthe start of the first Vand `"thestart of the second reduction varies in'V proportion tothe `train leng'jth,` since the timing reservoir 8`becomes charged to a prof portionately lower 1 degree of Ipressure when Y a trai-n is short, lbecauseitherdischarge valve 7-fis open for .a shorter peiiodzofitirneto elect theirst reduction inlthebrakepipepressure of said shorter train. Since ffitfrequires la shorter period of time-to reduce said lower kvtiinini'b'r reservoir v.pressure:totlie degree at Lai() .which the second reduction is started, the ;tetal time 'from ,the ,start of the first to #the start odi-,the second-i'eductionfistliusless ona shoittitnainf than? itfis onv ai long@ train. i

t the fliiidtunder=- pressure: supplieditoith yspl t .reduction devicethi'ouglr.pipe Z9'sliould :fai for.* a-ny-fcause, sliehpa's the breakin-g of pipe7'9,,;tlien l. if an automaticcapplieationof the fbrakes f occurs, :the bold-back portion 33 of ltbe split rediictio'n `device willy not zbe operated .toseparate passagesiQSf ands99 fromthe .rstandsecond reduction reservoirs 96 ruicll?y respectively. Gonsequently, when .an auto- ,matifclbiiakeapplication isv initiated, tlierfiluid ,undeiwpressure filoni-the equalizing; reservoir ,f1.0 `-Wi/Ll', attlie saine time, y:flow and equalizeinitobotli tlletirstand second reductiony reservoirs, thereby causing aiulliand'continuous ,serviccwbrake Il plication;

-`lVliileoneillustiiative embodiment of vthe invent-,ion has been described .in detail, it is `notenri tentionito limit its scope ico/that epibodipgient or otherwise than by the terms of h6/m21 @ended claims. gllavginginow ,describedl our inventionwwliat We claim as ne-W' anddesire to secure 'by Let-l ters Batent,fis,:-' e

AA1 aparatos foiefeetingf 21 l'reduction sin brake ,pipe pressure 'ini two stages `including a iii-'str iictionn servl, la ,second` reduction rese r, valve oneens e :normally connecting sa-id L eservoirs; an equaflizingwreservoir, an vappli-cation valve i device r movable, 1 to 'applis cation i P DSit-ion ,to connectV theirst vreduction' ,reservoir with the Aeqnaliziiigfpreservoir, and

`mea-,ns Aiiin-n3ediately responsive :to :the Amovement Joli said "valve, device E rto, application -po- Siton afer operatingzsaid valve meansito out. -ofl' communicationbetween the first and the seCQndiedpction reservoirs. .n

:2. ,Apparatus for electing :a reduction inv bike pipe pressure in two-stages including j a irsft reductionV reservoir, a :second reduction l reservoir, `valve means normally connecting Noi-r, :valve ,means inornially connectinggsaid trese-irvoiirs, anzlequalizi-ng'freseizvoir, ian' lappli- .cation .valve Ydevice movable to Aapplication positionV which/the qualizingireseivoir is i connect-enigtoA tliefii'st'.reduction reservoir, and

Va valve fdervice'f responsive Sto .an {incre-ase in yfluid pressure and controlled :by said appli ,1. eration' `vialve devi-ce lier; electi'ng :the inlovementof said `valve means sofas toont off; con in'nmgeationbetween the first, and the second reduction reseivoirs. f

e ,14. :The r'combination Avith apparatus 'for effect-ing 2a reduction ;in",fbrake pipey pressure in tivo stages'incliiding a :iirst reduction reservoir, :a lsecond' reduction `rcser` `.-vo1i, valve :means normally. connecting said `reservoirs and operated by an' inerezre in Huid pressure for-' cuttingoff .communication between :said reservoirs, an equalizing reser- .reser voir, and :a valve devicezoperated-'byan increasey in fluid vpressure and .controlled `:by

said application `valve device jfor ellecting ,an

inereasein Vpressiu'e on said waive: ineens. r m Y .L n f f o. ille combination ,with 'brake pipe, of

vapparatiis forv :effecting a reduction .in brake pipe pressoreinv tivo stages, f including .-a #first re diiction reservoir, a .second yreductifm cessi'- voiif, valve lmea-.ns .normally conneetingsaid reservoirs, a timing reseriioii,agvalveldevice,

`subject toitlie pressure in said timing-.reservoir and.- initially operatilvejtoieiiect tbe `movement of vsai d* Avalve means t tozcut jo'll communication between .theirst and ltlie second reduetionlresgerlvoirs, said ivalve' device @being operated Liuponia"predetermined increase in pressiire'in `4:at-he .timing reservoir Afor edecting the kInovenlent ,of- `Said valve' means .seas 4to connectatlie tlirst and second vre',diietioniReservoirs. g.

6; The-combinationwithay brake pipe, ort apparatus 1 for eiecting a liediiction :in f :brake pipeypressuie in twoA stages, inclndinlga ii-rst reduction reservoir, a seeoiefdr reduction reservoir, valve means l normally 'connecting ysaid reservoirs, an -equalizing vrveiservfo'irg a disrcharge'.valve mechanism, means yfor connectxvoii, lan Aapplication valvede'vieefmovable:to applicatimi-T position in which the Aequalizing .reservoir 1s connected -fto .atlie first .ieductaon ring yeqlializing reservoir :to the lirst iret 4duction reservoir orfoperatingfsaid discharge valve ineelianisin to ventfluid froinft-be bralie pipe, and'm'eans 'oreiiectingltlie operation of` said'- valve nieansto out off'communication between therst and second rediiotion reservoirs in advance of .the .operation of Y't-liedischarge valve mechanism to vent lfluid from/the brake pipe.;l i J f,

7.'The,combination with aibrakepipe, of .apparatus Jfor effecting afreductioninflow/kc pipepressure iny two stages, *including a.- first reduction reservoir, a second-re'dctionrescrveil-,valve means normally connecting 'said reservoirs, anxequalizing reservoir, -a disy charge valvemecha-nism, and means operative to co'nnectfthe equalizing.reservoirWitlitlicgo y `reir und norinsllr connecting the il 1., A, j second reduction reservoirs, and operzued -upo'n a, predetermined increase in pressure tirstreduetion reservoir and to elicottlie operation o'tsnid valve means to eut oit communication betweenthe irst and second reduction reservoirs. ,Y i i y i 8. The combination with a lnuie pipe, ot apparatus vfor e'tiiectino a Vreuluction in uralte pipe pressure in two l. iin-iruling n. iii reduction reservoir, e scoor reduction" reser vor a timing reservoir, sud evasive device uliject-to the pressure in said timing 'rosen und in said timing; reservoir vfor eutting` oit' communicationl between the iirst and second reduction reservoirs.

riflie combination with :i apparatus :tor etleeting n reduc n in broke pipe pressure in two includingn tirft` l. su uction re d tiren et a apparatus for eti'ecting a reduction'in vo1-alie pipe pressureiin trito stages iucludinpg'a first reduction leser-veine Second reduction res-- ervoir, timing reservoir, ovaire device sub- `ject tothe pressure in said timing reservoir. 'und normally connecting the ti st and seconc reduction reservoirs and'operated upon s. predetermined increase in pressure in sai d timing reservoir kfor cutting oli eonnnunication. lietween the first and second reduction reservoirs, and a valve device first operated upon the char-ging` of one side high rate and thev other side nt a 1iower rate or'efieetingtlie charging* oi saidl .timing reservoir et a lnglr en'operated to etiect the charging rete, and tl oli said timing` reservoir at n, slower rate;

' ll` The, combination"with n, ln'nlre pipo, ot :ippsriitus tor etiie'ctiii'e a reduction in brake pipe pressilre `in tnofstages rinc-ludinp; aV first reduction reservoir,v a second rered'uction reservoir.,v a timing reservoir, a vali/e device subject to the pressure in said timing' reservoir and normallyv connecting; the

first 'and second reduction reservoirs and op erateel upon a. predetermined increase in pressure in said timing reservoirffor cutting ott communication between the iirst and second reduction reservoirs, and s` Valve device Vtor Controlling' tlieielinrging ot said timing; res! eri-voir and also operative to efeottlie movement of said reduction reservoir contiiollmg valve device to eut ott con'nnunieation benveen rire pipe, etY

n reservoirs und operated upon e pre'-t fpparatus for effecting a reduction infbralre pipe pressure in tivo staoes ineludinga valve thriving apos'ition for effecting a first tion in brake pipe pressure and a position tor electing a second reduction in limite pipe pressure, a timing reservoir connected to one side oft said valve device, ind Valve means having one position in Winch the opposite side ol" seid valve deviceis supplied with fluid .under pressure and rin which said timing;r

-rvoir is charged at a-hieh retenn'dznin other position in which said tuning; reservoir ls charged at e slower rate The combination with s brake pipe, of

apparatusfor eteeting a lreduction in brakey lpipe pressure 1n two stages including-a valve device Vhaving a tn'st stage posit-lon and a lso second stageposition, means tending' tomainrain said valve device in its ralve means operated upon a predetermined increase inpressure m said'reservcmf` `tor effootingl the ii'iovement of saidvzfllve device to its second stage position.,A

l. The combination `rwith a brake pipe, of

pipe press re ii'itWo stages il'icludineT a Valve device having' a lirst stage position und a second stage. position, means tendingto maintain said'valif'edevice in .its iirststage post 'tion While duidfis being' Vented from the brake pipe in melting; the lirst stage reduction in o brakey pipe pressure, `a timing reservoir, and

valve ineens operated upon a'predetermined increase in pressure in said reservoir for efiectine" the moven'iento said valve device to yits second kstage position regardless of Wiietlii ,erf'luid isbemgventedfrom the brake pipe. y i5. The combination with a brake pipe, of

apparatus tor eiiecting a reduction in brake pipe pressure in tivo stages including` a valve device haring; n position for effecting a irst reductionin brake pipe pressure and a .positioniier effecting a second reduction in brake pipe pressure, a valve mechanism for ventingr vtive in' aI predetern'iined time if said valve mechanism tails to open to vent fluid trom vthe lirele pipe after the brake application is lnntrated vfor effecting; tlielnoveinent ot said Valve device to its posit-ionfor effecting an spplication oi? the brakes in two stages.

1G. `The Combination with a brake'pipe, of apparatus for effectingl a reduetion'in brake pipe pressure in two stages including' a Valve device havinga position for effectingr a first 'first stage posi-kry `tion While Huid is beine; ventedirom the brake `pipe infmaking the Vfirst stage reduction in brake pipe pressure, a turning,r reservoir, nud

.fluid iromtlie brake pipe, and means operay reduction in brake pipe pressure and a posii tion for effecting a second red,ucion in brake pipe pressure, a timing reservoir, valve vmeans controlled' by.v the pressure infsaid timingr reservoir for controlling;- the operation ofso/id velvedevice, a second tuning: reservoir, :ind valve means controlled by tliepressure in timing,ieseiveiigw'aive ineens subject to the said second timing` ieseiveii foi' also controlling' the operation of said valve device.

17. The combination wih ai bi'zike'pipe, of

iing' the operation ofsziid Valve device, :il zhiie iiiniing i'eseifvoii'7 ind Valve. ineens 'subiee valve device.

pipe pressure in two singes including a Valve device "for Controlling the initiation of the second reduction in bi'aike pipespiessuie,v zi

t to the piessuie in Suid third tin'iingiesei'` ye if ei aiseeenti'olling the operation of Said y 18. The combination with a bi'ake pipe, .of appare-.ins 'oi eieeting a reduction inbreke pfessni'e in said reservoir' for controlling the ep'eizitien of Said valve device? und ineens .iOi' charging said"ieseivoii; at yone time it one iza'ie and :it niiohei @infie at another rate.-

pipe piessni in iwors'ziges including a vzihe de'iiee im eeiiti'eliinp; die initiation of the Second iedii en infrbiake pipe .ies 1ni'e. a

`tinfiinf i'eseiweii valve means si-ib'eeteto the lepeiaizien 0i: Said vulve Jdevice, ineens foi' Charging-filieiefseivoii at :i n pie-determined ,rzite,end ineens opeiaed Upon Veniingfflliid lfiioni the brake pipeiii eeetiiigthe .first yiedueien in.V bi'zikepipe piessme for Charging;

said ieeeivoii :it n' higher ratei. n

In testimony Wheieof'we have hereunto set kein' hands-this Ghd'fif/ of Oetebeij, 1927.

*iii-ienne ii; 'iiiOi'iASf CLAUDE ii. NELSON. 

